High and low voltage alarm equipment



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Jan. 29, 1929.

C. E. LOMAX HIGH AND Low VOLTAGE ALARM EQUIPMEM Filed July 1, 1922 "m be Patented 29271929 Y y UNITED STATES 1,700,540 PATENT- OFFICE.

LOMAX, 0F CHICAGO, ILLINOIS, ASSIGNOB, BY `MESNE ASSIGNMENTS, i TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, 'A CORPORATION O F DEL- AWARE.

HIGH AND LOW.' -VOLTAGE ALARM EQUIPMENT.

applicati@ mea my 1,

The present invention relates in general tol high and low voltage alarm equipment, but is concerned more particularly with the pro` vision of equipment for actuating an alarm l' when -the volta e of a storage battery rises above or falls below certain Apredetermined values.'`

An object of the invention is to provide equipment for accomplishing the above which 10 is of simple construction, and more positive in operation than was heretofore considered possible.

A further object is the provision of equipment which iswell adapted for use in con- 15 trolling automatic charging and voltage regulatin systems.

A rief description of the nature of the equipment shown in the drawing will now be ven, so that a better understanding may adof the detailed description of operation which is to follow.- Referring to the ,Y drawing, in which has been shown by means of conventional circuit diagrams one manner of carrying out the invention, alarm signals A. and A. may be of any desired type, but as shown are ordinary vibrating bells.' Relays 2, 3, and 6 are of well known type used in telephone systems. rllhe relay 2 has a copper lug on the armature end to make the same slow to pull up, while the relay has a copper lug on the heel end to makeit slow to release. The thermostat T is of well @own construction, vand is adjusted to operate to close its contacts 7 once about every three to vfive seconds. Relays 5 and 4 are the high and low voltage testin relays. In order to insure permanence o adjustment relays of the gravity type should be used, as the relays of this type are not appreciably aected by changes in temperature. With respect to the windings of the testing relays, good results have been secured by winding to 315 ohms resistance with No. 26 Advance wire, although it is to be understood that the invention is not limited to. the precise resistance or the particular type of wire mentioned.

. A detailed description will now be'given,

and for this purpose it will be assumed that a 48 volt battery is used. lIt will lfurther be assumed that an alarm is desired when the batte voltage falls to-46 volts, or rises to 49 vo ts. Under control of the thermostat, relays 4 and 5 test the battery voltage periodically as described below.

A circuit is originally closed for the heat- 1922. serial no. 572,312. i

ing element 11 of the thermostat T. In a few f seconds the thermostat operates, and closes at Vtery'voltage reaches 49 volts.v Relay l4 in operating shunts battery from relay 2 while the operation of relay 3 causes ground to be removed from the heating element 11 of the thermostat T, the same ground being switched to(the windin of relay 2.- As previously stated, battery 1s shunted from relay 2 b the operation of relay 4, and therefore re ay 2 70 cannot operate at this time. As soon as the thermostat cools suliiciently, the operating circuit for relays 3 and 4 1s o ened at contacts 7. Y The relay 4 falls back s ightly before the relay 3, causing the shunt to be momentarily removed from relay 2, but relay 2 being slow to pull up is not actuated at this time. The relay 3, being sluggish infalling back, acts to slow up the operation of the thermostat T. As soon as the relay'3 falls back the operationsl above described are repeated. -It will now be assumed that the battery potential has fallen to 46 volts or lower. This time when the contacts 7 of the thermostat T close, relay 4 will not be operated. The relay 3 however, `operates as before to remove ground from the thermostat T, and to appl lthe ground to the winding of relay 2, whlc latter relay will now operate. Relay 2 in op-A erating, at Aits lower armature completes a locking circuit for itself, through the key 8 to ground, and at its up er armature applies ground to operate the a arm signal A. The. operation of the alarm A informs the attendant that the battery voltage is low whereupon the attendant stops the alarm by operating key 8, and then adjusts the voltage by cutting out counter cells, or by starting the charging equipment in any well known manner.

It will now be assumed that the battery otential has been increased to 49 volts. en this occurs, and the contacts 7 of the thermostat T are again closed, relays 3, 4, and

5 operate. The operation of relays 3 and 4 105 l prevent the'operation of the low voltage signal A, the same as if the battery voltage were at normal. The operation of relay 5, however, completes a circuit for relay 6, which locks up over a circuit similar to that of relay 11'9 2, and which at the same time completes an Voperating circuit for the high voltage alarm A'. The attendant upon hearingthe alarm A operates the key 8 to permit relay 6 to fall back, and proceeds to readj ust the voltage by cutting in counter cells, or by stopping the charge in any well known manner.

0n rare occasions it may occur that an excess amount o current is momentarily withdrawn from the battery, causing the potential to take a momentary drop to 46 volts. When this occurs it is not desired that the attendant be required to operate the key 8 to stop the alarm, nor is this necessary, for as soon as contacts 7 again close relay l will energize the battery voltage having risen to normal and will short 'circuit relay 2, causing the latter relay to restore.

Although the testing system herein described has been illustrated in simple form,

as having the tunction ot operating high and All) . tary testin as distinguished from the perlow voltage alarms, it will be understood that it -is so shown merely tor convenience, and that in practice it may be used in connection with any oit the well known types of voltage regulating and automaticbattery charging systems employing high and low voltage relays to control the cutting in and out o the counter cells and the starting and stopping ot the charging apparatus.

llrom the foregoing it will be seen that l have devised a new and highly improved apparatus for closing an alarm or other circuit when the voltage ot a storage battery or other source ot potential falls below or rises above certain predetermined' limits. `The principle advantage l claim for the invention is due to the use ol normally deenergized testing rela s which are periodically connected across t e battery instead ot being parman nentlybridged', and which, referrin particularly to the low voltage testing re ay, 'enen gize rather than deenergize to indicate an abnormal voltage. Normally deenergized high voltage Arelays have been used betere, but so lar as ll am aware low voltage relays have previously all been ot the normally energized t pe re uired to ilall back when the volta e alls be ow the limit. These relays are diiiicult to adjust and'uncertain in oper-v ation, andthe present invention, therefore, which uses'a normally deenergized relay, constitutes a decided improvement. .A further advantage which should be mentioned is moreor less incidental to the scheme of moinen marient bri ge arrangement.. Since the testina ' across the battery they ma be o relatively low resistance, and it 1s we l hown that low resistance relays are in general more accun rate and positive in responsel than relays ol relatively high resistance.

Having described the invention, what'l consider to be new, and desire to have pro.-

' relays are not permanently bridged tected by Letters Patent will be pointed out in the appended claims.

What I claim is:

1. ln combination, a source-ot` current, currenttest and alarm equi ment including a pair of alarm control re aysv and circuits therefor, operatingv means for completing an operating circuit or one of said alarm control relays, means operated by said alarm control relay for opening the circuit of said operating means and for closing a circuit for the other alarm control relay, and means operated when the potential of said current source is normal for preventing the operation of said other alarm control relay.

2. lln combination, a source otcurrent, cur? rent test and alarm equipment including a pair of alarm .control relays and circuits therefor, operatin means for completing an operating lcircuit or one of said alarm control relays, means controlled by said alarm control relay for opening the circuit of said operating means and for closing a circuit for the other alarm control relay, and a test relay connected in parallel with one ot' said alarm control relays lor rendering the other alarm control relay inoperative.

3. The combination of volta e testing equipment with means for periodically conf necting the equipment across a source ot current, means operated by said testing equipp ment tor controlling said connecting means, and means control ed by said connecting means to in turn control the connectlon of the testing means to said source.

l. ln an alarm signal device, a battery non mally ot one potential, but subject to varia tion. above and below said normal potential, a battery 'testing relay, another relay, an alarm relay, an alarm signal, switchin means tor including said battery relay an said other relay inthe circuit ot said battery, means operated by said other relay to render said switching means inedective and to close.

a circuit for said alarm relay, means pperable bi said alarm relay to close a circuit for said' a arm signal, andv means controlled by vsaid battery relay tor preventing the operation of said alarm relay.

5., lin a volta e testing and signalling device a, storage attery normally ol one poicc tential, a test relay connected to said battery in a series ot successive tests, an alarm relay, means for operating said ala relay on a test when the potential of the batteryl 

